Payment methods per booking site.
If you have no credit card you have certainly one or more of the social payment cards or accounts.
With these, you can book on the sites listed here below. Keep the list at hand when you book your flight.
Accepts payments with:
DEBIT AND CREDIT CARDS
We accept the following payment cards: American Express, AIR FRANCE KLM – AMERICAN EXPRESS, Diners Club, Maestro, Mastercard, Visa, Visa Electron and UATP / AirPlus.
But then you must book at least 16 days from beforehand.
WESTERN UNION QUICK PAY
PAYPAL (not authorised for flights to and from Cuba)
Credit card, debet card (Maestro), Bancontact, Paypal
Credit cards and Paypal (Paypal without the need for a credit card being linked)
Next booking sites accept credit card only and are thus to avoid when you have no credite card:
Wizz air or kiwi